Author: Gian-Carlo Pascutto
Date: 12:58:09 11/04/02
Go up one level in this thread
On November 04, 2002 at 11:32:53, Robert Hyatt wrote:
>>If it spends 20% of it's time for this (a realistic number
>>on a high end P4) and the parallel speedup is 1.7 then it
>>is going to run about 5% faster with SMT, roughly.
>
>Where does that "math" come from? (5%)
Assuming the speedup comes from that 20% waiting time that
can be eliminated, and your parallel efficiency is 1.7, I
do 1.20*(1.70/2) and arrive at a speedup of eh, 2%.
(I realize this is quite fuzzy math)
>I have seen a 30% improvement
>in NPS using hyper-threading on a 2.2ghz PIV. That should translate into
>a roughly 20% improvement in search speed to a specific depth. That seemed
>to be close to the numbers Eugene posted as well.
Why is it so much? Is Crafty so memory-bound?
>Once I have time to fiddle with the locks to add the pause, I expect even >better performance...
I use this, works fine with Intel C
__inline void Lock (volatile int *hPtr)
{
__asm
{
mov ecx, hPtr
la: mov eax, 1
xchg eax, [ecx]
test eax, eax
jz end
lb: pause
mov eax, [ecx]
test eax, eax
jz la
jmp lb
end:
}
--
GCP
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.